The invention relates to a mounting arrangement for electromagnet driving structures in a mosaic needle printer head, in which such structures are adjustably mounted on a supporting frame, employing resilient elements and provided with a screw adjustment.
The invention is of particular utilization in recording or printing machines such as teletypewriters, office and data recording machines.
In the recording of characters upon a recording carrier, for example, of paper or the like, by means of mosaic needle printer heads, with or without the utilization of ink ribbons and the like, it is necessary to arrange the needle printer head at an optimum distance from the recording carrier. The precision of the adjustment of the distance from the recording carrier becomes of increased importance when a specific value is required for clean, even recording, particularly when high typing velocities are desired.
As the needle printer heads comprise a plurality of individual parts, it is necessary not only to take into consideration the adjustability of the head itself but also the adjustability of the spacing of the ends of the individual printer needles with respect to the printing or impression location. The length of the individual printer needle elements is subject to tolerance errors and the drive structures for the needle elements likewise involve mechanical tolerance errors. The various tolerances have different initial characteristics, the effects of which must be equalized or balanced by corrections in the distance between the printer needles and the impression points. Likewise, the wear of the impact ends of the printer needles is different in dependence upon the position of the printer needles within the printer head and in dependence upon their individual operating frequency, so that a corresponding subsequent adjustability is desirable.
These problems are known and arrangements have been devised taking these facts into consideration. Thus, for example, German Offenlegungsschrift No. 2,430,440=U.S. Pat. No. 3,907,092 discloses a construction in which the individual plunger type armature electromagnet structures are adjustably supported in the frame of a mosaic needle printer head by means of a threaded or screw connection. The mosaic needle printer head, utilizes plunger-type armature elements in the individual magneto structures with the latter being adjustable, in the displacement direction of their plunger-type armatures, by rotating the respective structures about the axes of their armatures, utilizing suitable threaded screw connections. The final adjusted position is maintained by the use of a suitable lock nut. However, in order to effect an adjustment of the individual magneto structures, it is necessary to disconnect the electrical connections thereto. Consequently, an adjustment of the structures during a test operation is not readily possible, complicating subsequent adjusting operations.
In a mosaic needle printer head utilizing a drop-type armature structure, it is known, for example, from German Offenlegungsschrift No. 2,256,813,=U.S. Pat No. 3,842,955 to effect adjustment of the individual electromagnet structures relative to the supporting frame of the mosaic needle printer head by a screw adjustment arranged in opposition to a spring biasing element. While such an arrangement provides a very simple axial adjustment of the electromagnetic structure, the position of the electromagnet system relative to the supporting frame is essentially dependent upon the spring element supporting the bearing surface. Tilting moments, occurring during the operation of the electromagneto systems are merely reduced in a cushioned manner, i.e. a firm or braced support is not adequately provided.